The present invention relates to a disk address controller and, more particularly, the one for effectively controlling a disk unit commonly used in a plurality of processing units or programs.
In the uniprocessing system, when a single disk unit is used independently by individual programs, it needs a sub-routine program for supervising enbloc the information concerning the disk by software, such as, for example, the physical address input/output control system or the logical address input/output control system. This means that the disk device is necessarily controlled through the program routine. Therefore, the time loss of the overhead considerably deteriorates the efficiency of the computer system.
In the multiprocessing system, when two processors independently execute programs, the area of a main memory unit connected with the multiprocessing system must be properly divided and the resource of an input/output unit must be properly assigned for two processors. In large-scale systems, no problem arises with an arrangement that a plurality of disk units are connected to the system and these disk units connected are allotted to the two processors, respectively. In small scale systems, however, since the area of one disk unit is divided and assigned for the two processors, one processor must be operated constantly taking account of the operation of the other processor. Further, when the system is enlarged with expansion of the capacity of the disk unit, it is necessary to greatly modify the program stored in the disk unit.